America is now following the lead thus set, and all the most important lines in the United States have adopted block working and interlocking, but a great deal still remains to be done.
While it is throughout essentially a mountainous country, very complicated in its orographic features and interlocking river systems, two principal mountain axes form its ruling features - the Rocky Mountains proper, above referred to, and the Coast Ranges.
This law has important ethical and political bearings; but in the province of disease this advance of what may be compared to the interlocking of points and signals has had wide influence not only in altering our conceptions of disease, but also in enlarging our views of all perturbations of function.
The inspections made by the officers of the Board of Trade under this act are very complete: the permanent way, bridges, viaducts, tunnels and other works are carefully examined; all iron or steel girders are tested; stations, including platforms, stairways, waiting-rooms, &c., are inspected; and the signalling and " interlocking " are thoroughly overhauled.
But the soldiers, crowded together shoulder to shoulder, their bayonets interlocking, moved over the bridge in a dense mass.